FIG. 1 shows a typical modern telecommunication network that comprises a very high capacity back-bone optical fiber ring 100 that typically runs nearby the largest cities 102 that forms a part of the national core network. Connected to the national core network are metropolitan fiber rings 104 that surround the cities at several levels and connects to a local central office (CO) 110. The central office 110 houses switching equipment or a telephone exchange 112 and is the point to which subscriber home and business lines 120 are connected to the network on what is called a local loop. Many of these connections to residential subscribers are typically made using a pair of copper wires, also referred to as a twisted pair, that collectively form a large copper network operated by the telecom provider. Within the CO 110 the line connections between the exchange side and the subscriber side are terminated at a main distribution frame (MDF) 114, which is usually the point where cross-connections between the subscriber lines and the exchange lines are made. In addition, similar cross-connections may be located in sites closer to the serviced areas such as a local residential area, that are known as drop points and cross-connect cabinets. Furthermore, MDF 114 usually holds central office protective devices and functions as a convenient test point between the subscriber lines and the Office.
Virtually every aspect of the telecommunication network is automated with the notable exception of the copper network. Management of the copper infrastructure is a highly labour intensive process that results in one of the most significant costs faced by telecommunication providers today. By way of example, when a new subscriber requests a service such as a new phone line, technicians are dispatched to a CO 110 to manually add jumpers to the main distribution frame to activate the line. The same level of labour is required when a service is to be removed or modified. This manual process is naturally prone to errors since the technician can inadvertently make incorrect cross-connects that can delay activation of new services, or cause a temporary loss of existing services. Over time as these wires can accumulate to become such a mishmash to the point where a complete rewiring is required. This would impact current services and could result in increased customer dissatisfaction and leads to unnecessary operational expenditures in expensive labour costs.
FIG. 2 shows an exemplary central office MDF cabinet that comprises columns of line termination blocks or connector blocks where the lines from the exchange 112 terminate (or connect) in the MDF at the exchange side termination blocks 210. A column of termination blocks 220 are located on the line side of the MDF coming from the subscriber lines. The cross-connects are made by physically placing a jumper wire 230 to connect the appropriate line from the line side to the exchange side. In practice there may be several columns or stages of termination blocks on either side of the MDF whereby all line pairs may conceivably be connected with a jumper lines that bridge the line and Exchange blocks thereby leaving behind a disorganized jumble of wires that is often difficult to manage.
Another issue with the current manual intensive process is that technicians must often go to the distribution frame to manually analyse or test lines in the copper network. For example, during service initiation a technician must manually connect test equipment to verify the accuracy of the circuit installation. In some instances, verifying and testing connections becomes significantly more difficult if over the years improper connections were made that were not correctly logged. Troubleshooting then becomes inordinately tedious, time consuming and expensive. For telecommunication providers holding down costs has become a significant priority, especially in today's competitive deregulated environment.
It has long been desired by service providers to reduce the amount of labour required to maintain and manage their copper infrastructure. An area that has held much interest is to automate many of the manual tasks currently associated with MDFs such as making/breaking cross-connections for service initiation/removal and network management and testing. In this vein there have been attempts in the past to automate MDFs using various technologies, each suffering from limitations that have rendered them uncompetitive and thus have not been deployed on a wide scale.
One technology that was investigated is an electromechanical solution using metallic relays as a means to automate cross-connects in MDFs. Although the use of electromechanical relays have been used in conventional telecommunications equipment for many years and have proven reliable for use in e.g. voice switches, the limited switching capacity of matrix boards constructed with relays has been a problem. In practice it is difficult to construct large switches with relays because the size of the individual relays are relatively large. This is mainly due to the relatively high voltage levels used that limit the level of miniaturization for mechanical devices. Thus a MDF servicing a fair size CO may require millions of relays for suitable connectivity, would be expensive to maintain, and occupy far too much space to be economical. Consequently, MDFs based on this technology never really got implemented for large-scale applications.
Another area of previous interest is automation by use of robotic solutions. Robotic technology is used to physically remove and insert pins in holes within a matrix board to make the various cross-connects. Automatic pin inserting/removing robots operate by using a pick-and-place mechanism to automatically insert pins at the desired hole locations in the matrix board in order to selectively connect subscriber input line pairs to multiple CO lines. Although the robot mechanism can be extremely accurate to within tenths of millimetres, the mechanism head requires movement along three axes necessitating a drive motor structure that is relatively complex. Furthermore, the mechanical components are subject to reliability and maintenance issues due to the numerous moving parts. Service providers take these issues very seriously since costs can quickly escalate if the equipment constantly needs to be attended to. In large size COs or those experiencing significant growth, reliability issues become even a greater concern and therefore the technology had never become viable for deployment on a large scale.
Another major disadvantage of the prior art solutions is their lack of flexibility to easily scale the size of deployment, since various telephone exchanges and central offices often vary widely in size. For example, central offices outside of major population centres such as those servicing rural areas, may experience relatively slow growth and are somewhat stable in terms of new connections. On the other hand, central offices in densely populated urban areas may experience tremendous growth in orders for services such as xDSL and the like which tend to expand at high rates. Deployed MDFs must be able to operate economically and be able to cope with conditions of high growth. The solutions of the prior art fail to provide adequate provisions for dealing with high growth since e.g. the size of the matrix board that a robot can traverse is generally fixed and is difficult to enlarge without completely replacing the equipment. Such growth requires significant capital expenditures and substantially increases the complexity to the network infrastructure.
While automated cross-connecting technologies have existed for some time, none of the prior art solutions have been able to fulfil requirements for cost-effectiveness and scalability as required by telecom service providers.